import java.util.Scanner;

public class demo05 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n + 1];
        for (int i = 1; i <= n; i++) {
            arr[i] = sc.nextInt();
        }
        int[] dp = new int[n + 1];
        dp[0] = 1;
        for (int i = 1; i <= n; i++) {
            int max = Integer.MIN_VALUE;
            int min = Integer.MAX_VALUE;
            for (int j = i; j > 0; j--) {
                max = Math.max(max, arr[j]);
                min = Math.min(min, arr[j]);
                if (max - min == i - j) {
                    dp[i] = dp[i] + dp[j - 1];
                }
            }
        }
        System.out.println(dp[n]);
    }
}
